Method of impregnating wooden golf club heads



Unite States Patent O METHOD OF IMPREGNATING WOODEN GOLF CLUB HEADS Emil J. Marciniak, Easthampton, Mass., assigner to A. G. Spalding & Bros., Inc., Chicopee, Mass., a corporation 'of Delaware Application December 17, 1957, Serial No. 703,343 7 Claims. (Cl. 117-579) This invention relates to the method of impregnating wooden golf heads with vinyl resins for rendering the head resistant or immuneto the effects of moisturev such as swelling, deformation, and eventual deterioration, and otherwise to improve its physical character, to change its physical properties, to toughen it, and generally giving it those characteristics which it is desired to have imparted therto.

Heretofore heads have been impregnated with materials but they did not have a low moistureytransmission and did not prevent swelling. Also a method has been employed in which a fluid polymerizable non-stabilized resin or monomer is used in such a manner as to allow the monomer to polymerize after it has penetrated into the wood, with the attendant dificulty of controlling polymerization.

This method has a major drawback, namely resin higher solid content of the solution to be used and still achieve the desired penetration. Thereafter thehead is removed and partially dried at room temperature and then completely dried at an elevated temperature as before.

By so impregnating the head I am able to control the weight of the head so as to eliminate unnecessary coring in yorder to insert weights as has been the prior practice; I am able -to produce a more stable head in that the fibers in the head are adequately coated with the resin; an improved toughness of the material of the head is achieved, all with the added result that the headhas a low moisture transmission `and is more resistant to taking on moisture and swelling in use.

Other 4features and advantages will be apparent from the specification and claims when considered in connection with the drawings in which:

exudation, which may occur subsequent to penetration and after the heads have been removed yfrom the impregnating bath to be dried, with undesirable surface tackiness accompanying such exudation. This `has been a problem of long standing which heretofore required special and expensive Ifinishing treatment steps.

It is among the objects of this invention to provide improved methods of irnpregnating a golf club head whereby the .treatment is controllable to achieve uniform deep penetration into the head as well as optimum and lasting moisture-resistant resin impregnation of the article without the accompanying exudation and surface tackiness heretofore experienced. Y This is accomplished by employing an impregnating resin in the form of :a vinyl polymer or copolymer thereof in a mixture of solvents of the class of ketones and of the class of aromatic hydrocarbons, preferably such solvents having different vapor pressures and different evaporation rates at room temperature so as to provide an impregnating solution of low viscosity and high penetrating power and by subsequently controlling the rate of evaporation of the solvents from the club head in a manner to discourage and avoid resin exudation.

In one form of the invention employed yfor impregnating the heads, the heads are immersed in a bath of the impregnating solution at atmospheric pressure for a predetermined length of time suiiicient to permit the desired penetration, after which the heads are removed and subjected .to a partial drying at room temperature during which time the ketone solvent evaporates more rapidly than ythe aromatic hydrocarbon solvent from the surface of the head and, in eiect, builds up a resin barrier which prevents exudation of the resin when the heads are thereafter subjected to a drying period a-t a high temperature to complete the evaporation of the solvents therefrom. p

Another method of forming the heads is to subject the heads to vacuum until a stable condition is achieved and thereafter impregnating the head at high pressure with the impregnating solution. This procedure greatly shot-tens the time for treating polymers thereof maybe used. These resins are suchv Figure 1 is a side view, partly in section, of a wooden golf club head.

Fig. 2 is a top view, partly in section, of the head.

Fig. 3 is a sectional view taken on line 3 3 of Fig. 1.

The golf club head 10 is made of wood, preferably persimmon, and is shaped to ythe required shape. It is then impregnated with an impregnating solution comprising a polymerized resin and a mixture of solvents 0f the class of ketones and of the class of aromatic hydrocarbons, which solution has a low viscosity and high penetrating power so that the impregnation will extend into the head a substantial distance `from all faces thereof as indicated by heavy shading in the sectional views .of the drawings. Alfter the solvents have been removed, there will be incorpororated vin :the head the polymerized resin so that the head has a low moisture transmission and is resistant to swelling in response to moisture surrounding the head.

Prefer-ably, the polymerized resin comprises polyvinyh idene chloride (Geon 222) although vinyl polymers and copolymers thereof such as polyvinyl chloride and cothat when impregnated into the body of the head tend p to coat the wood fibers and 'to toughen Ithe head. Also,

heads impregnated with polyvinylidene chloride particularly have a low 'moisture transmission and substantially resist the passage of moisture into the head and the wood fibers thereof so as to prevent. undesirable swelling of the head. The resin so incorporated in the head tends also to add weight to the head in desired amounts to control the weight of the head as required.

With -the heads of the present invention coring thereof,`

as now employed for the insertion of the usual weights in the head, is eliminated or greatly reduced.

the head and permitsa l The ketones used in the solution are those which dissolve the resin, reduce the viscosity of the solution, swell the'wood to permit better penetra-tion of the solution and have la high evaporation rate. While diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone and the like may be used, it is at present preferred to use acetone.

Ihe aromatic hydrocarbons used in the solution are those which have some solvent effect on the resin, cause the solution to have a greater penetration into the woodl and act to stabilize .the solution. Also they are the ones which can be readily evaporated from the head, althoughv they have a lower evaporation rate than the ketones. Examples of such `aromatic hydrocarbons are toluene aromatic and xylene aromatic.

It is at present preferred to have a solution with'za predetermined solid content which will readily penetrate the heads and yet which will supply the necessary resin in the finished head to produce the desired results. For.

example, when the heads are impregnated at normal. atmospheric pressure, a 12% solution has been found to.` be highly satisfactory. This, of course, can vary slightlyy in either directionv depending upon the density and nature tween 24 to 27% r:have been found `most satisfactory.

However, here 'again this percentage may -vary slightly above and vbelow these values depending upon the nature of the head, i.e., the density of the wood and other 'characteristics affecting the penetration of the resin.

`t"`will be noted 'from the shading in the, drawings that the'impregnating resins extend a substantial distance in from each `surface of the head. With this depth of penetration, 'the grooves 11, 12 for the usual face plate 13 and sole plate 14 in the face'l 'and bottom surface 16 can jbe safely cut'since there is substantial resin content inwardly of thesecuts soVv that passage of moisture into theheadl through'the cuts is 'effectively prevented. llFurther .the face plate can be cemented in position by means of kan epoxy resin which not only adheres the face plate, which' may be 'of plastic, .ber or the 'like material, to thev head but also aids .in sealing the cut and preventing moisture frorrrpassing into the head. Similarly, the sole platesY can be adhered to the bottom by epoxy resin or lthey .can fbe'secured by screws 'When this is done, itis preferred to coat the screwwith an epoxy or equivalent resin to seal the screw holes as indicatedV by the shading in Figs l and 2 so that the passage of moisture along the screws and into the head is `substantially eliminated.

It will be seen, therefore, that I have provided a novel golf head of the wood type which isimpregnated with a polymerized resin, preferably polyvinylidene chloride, to an extent V'which effectively prevents the swelling of the head1 and which resin coats the fibers of the head to, in effect, seal them from moisture, and which is provided with a smooth outer surface since the impregnation of the head' by my novel method prevents exudation of theif resinjfrom the head during drying thereof. Y 'The head of the present invention can be tproduced by impregnation at atmospheric pressure or by a pressurey impregnation process. Each of these processes will be described and in order to clearly understand the processes specific valuesutilized in each are being given by way of example. t

"Inu the process wherein the heads are impregnated at atmosphericV pressure, the heads are permitted to stand ndfare `airdried for-a period of atleast a Week. They are' then immersed in a tank of impregnating solution for a period of approximately 66 hours. The solution comprises a resin, preferably a polyvinylidene resin (Geon 222) dissolved in a solvent comprising half acetoneand halfjtoluene.v The solution has a 12% solid content. Such afsolution can be produced from 5 gallons acetone, 5 'gallons toluene and 9.45 pounds of resin, whichsolutionis vigorously agitated during -the mixing thereof. The viscosity of thes'olution at 75 F. or room vtemperature is `19-2() seconds as determined by a Zahn No. 2 cup and thel specific; gravity is .881. Y

Afterv the heads have beenimmersed Vfor 66 hours they` are removed from the solution and are partially `dried at room temperature of between -l:00 F. for from 4. to 1 2 .hours and preferably for l2 hours at 75 iF. I

havefound that this is an'irnportant step in preventing exudation froml the heads. A kpossible explanation of this discovery is that acetone which has a relatively higr evaporation. rate, it being `about 5-1 with respect to toluene, is evaporated slowly from the surface ofthe heads .andthe .resin therein will setup a barrier to the exudation of the resin from the head as the remainder of the'solvent is driven off frornthe head. Higher temperatures at thistime would build up vapor pressures in the head and drive out the resin. The Vheads are thereafter finish-dried in a heating chamber kor hot room having a'good circulation of air thereinand being at a temperature` of approximately 150 F. for 24 hours or 125 F.

for 40 hours, after which the heads are removed and 'processed into Y golf clubs.

If the heads are to be pressure impregnated they are inserted in a vessel and vacuum of up to 25 inches of mercury applied to the vessel and the vacuum is maintained on the vessel for a period of l030 minutes or until the reading becomes stable indicating a complete evacuation of the heads. The vacuum is shut of and the impregnating solution is placed in the vessel under a minimum of pounds p.s.i. pressure. Since the impregnating material is being forced into the heads under pressure, it can have al higher solid content. At present, it is preferred to have a solid content of 24%. The heads are left under pressure for 24 hours and are .then'removed and air dried at room temperature for from 4-12 hours. Thereafter they are dried in the hot room at a temperature. of F. for 24 hours.

The feature of applicantsll novel methods resides iu- 1..The methodof treating wooden golf club headsy which comprises the steps of impregnating saidl head with a solution of resin dissolved in aV solvent mixture comprising a solvent of relatively high evaporation rate and higher boiling point and another solvent of lower evaporation rate and lower boiling point for a period of time Y sufiicient to attain a deep penetration of the solution into theJhead; partially drying the head at room temperatureto effect evaporation from the surface of the head or" the solvent of higher evaporation rate to form a barrier to exudation of resin from' the head during a finish-drying operation; and then finish-drying the head by subjecting :the head to an elevated temperature for a predetermined period to eifect evaporation from the head of Ithe solvent of lower evaporation rate.

' 2;'The method of treating wooden golf club, heads which 'comprisesthe steps of impregnating said head with a solution of vinyl resin polymer or copolymer thereof dissolved in a solvent mixture comprising a `ketone and v au aromatic Yhydrocarbon for a period of ,time sufficient to attain a deepen Vpenetration `of the resin; partially drying the head at room temperature to effect evaporation of solvent from the surface to form a surface barrier Vresistant to the exudation of resin from the head during a finish-drying operation; and then nish-dryingthe .head by' subjecting the head to an elevated temperature for a predt'ermined period to effect evaporation of there-r maining solvent from the head. Y

v3.' The method of `treating wooden golf club heads which comprises immersing the head at atmospheric pressure'fina bath of a vsolution of polyvinylidene chloride dissolved in a mixture comprising acetone Vand toluene for a period of time suhcient to attain a deep penetration of the resin; partially dryingthe headat room temperature to effect evaporation from the surface'head of the ketone to form a surface barrier resistant to exudation Yof resin `from the head during fa .finishing-drying operation; and then huish-drying the head by subjecting the` head to an elevated temperature for a predetermined period` to elect evaporation from the .head of the remaining solvent. .Y Y

` 2l. VThe method of treating wooden .golf club :heads which comprises the steps ofl subjecting the head to a-vacuum to withdraw air therefrom until a stable condition exists; applying, under pressure, an impregnating solution of polyvinylidene chloride in a solvent mixtureicom-V prisng a Vketone and an aromatic hydrocarbon for ape- Y riod of time suicient to attain a deep penetration of the solution; partially drying the head at room temperature to eect evaporation of the solvent mixture from the surface of the head to form a surface barrier to exudation of polyvinylidene chloride from the head during a finish-drying operation; and then finish-drying the head by subjecting the head to an elevated temperature for a predetermined period to etect evaportion of the remaining solvent from the head.

5. The method of treating wooden golf club heads which comprises the steps of immersing the head in a bath of a solution of polyvinylidene chloride dissolved in a solvent mixture comprising a ketone having a high rate of evaporation and adapted to lower the Viscosity of the solution, swell the wood Iand increase the penetration of solution into the wood and an aromatic hydrocarbon having a lower rate of evaporation and adapted to increase the penetration of the solution into the head and to stabilize the solution, said heads being maintained in the solution for a period of time suiiicient to attain a deep penetration of the resin into the head; partially drying the head at room temperature to eect evaporation from the surface of the head of the solvent mixture to form a surface barrier resistant to exudation of resin from the head during a finish-drying operation; and then finish-drying the head by subjecting the head to an elevated temperature for a predetermined period to eiect evaporation from the head of the remaining solvent.

6. The method of treating Wooden golf club heads which comprises subjecting the heads to impregnation in a bath of dissolved polymer substantially comprising vinyl resin in a solvent mixture of an aromatic hydrocarbon and a ketone providing a viscosity at 75 F. in the order of 19-20 seconds as Ymeasured in terms of Zahn No. 2 cup, and a concentration of the polymer in the ordery of 12%; maintaining said impregnation substantially at room temperature for a period of time long enough to effect a deep penetration; partially drying the head at room temperature long enough to eifect the evaporation of a significant portion or" the solvent mixture from the surface to provide a surface barrier to prevent resin exudation from the article; and then subjecting the article to a period of huish-drying at an elevated temperature long enough to effect evaporation from the article of the residual solvent.

7,. The method of treating wooden golf club heads which comprises the steps of subjecting the heads to a vacuum environment long enough to effect substantial evacuation from the wood of entrained air; subjecting the evacuated heads to pressure impregnation in a bath of a vinyl resin of a concentration of about 24% contained in a mixture of an aromatic hydrocarbon and a ketone substantially at room temperature and long enough to effect substantial penetration of the head with the resin; removing the heads from the bath and partially drying them at room temperature to effect the evaporation lfrom the surface of a portion of the solvent mixture to form a surface barrier to prevent resin exudation from the head;

and then subjecting the heads to a period of iinish-drying at an elevated temperature long enough to effect evaporation from the article of residual solvent.

' References Cited in the le of this patent UNITED STATES PATENTS 1,588,617 Rose lune 15, 1926 2,020,172 Cotchett Nov. 5, 1935 2,140,981 Botty Dec. 20, 1938 2,188,396 Semen Ian. 30, 1940 2,591,768 Austin Apr. 8, 1952 2,804,404 'I'hiessen Aug. 2.7, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,936,248 May lO, 1960 Emil J. Marciniak It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readv as corrected below.

Column 4, line 49, for "deepen" read deep line 55, for "predter'mined" read predetermined line 64, for nfiniShing-drying" read finish-drying column 5, line l6, for "of solution" read of the solution Signed and sealed this 25th day of October 1960.

(SEAL) Attest:

KARL H- AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents 

1. THE METHOD OF TREATING WODDEN GOLF CLUB HEADS WHICH COMPRISES THE STEPS OF IMPREGNATING SAID HEAD WITH A SOLUTION OF RESIN DISSOLVED IN A SOLVENT MIXTURE COMPRISING A SOLVENT OF RELATIVELY HIGH EVAPORATION RATE AND HIGHER BOILING POINT AND ANOTHER SOLVENT OF LOWER EVAPORATION RATE AND LOWER BOILING POINT FOR A PERIOD OF TIME SUFFICIENT TO ATTAIN A DEEP PENETRATION OF THE SOLUTION INTO THE HEAD, PARTIALLY DRYING THE HEAD AT ROOM TEMPERATURE TO EFFECT EVAPORATION FROM THE SURFACE OF THE HEAD OF THE SOLVENT OF HIGHER EVAPORATION RATE TO FORM A BARRIER TO EXUDATION OF RESIN FROM THE HEAD DURING A FINISH-DRYING OPERATION, AND THEN FINISH-DRYING THE HEAD BY SUBJECTING THE HEAD TO AN ELEVATED TEMPERATURE FOR A PREDETERMINED PERIOD TO EFFECT EVAPORATION FROM THE HEAD OF THE SOLVENT OF LOWER EVAPORATION RATE. 